AdamFrisch
11th Mar 2008, 01:53
Now, I want to preface this question with the fact that I'm just a layman and amateur with a technical interest. Here goes my genuine question:
It is a well known fact within the helicopter world that the bigger the main rotor, the less power it needs to produce lift. It also makes less noise, since it turns slower.
With this in mind, how come most GA planes have such small props? This makes them noisy and producing less thrust. Why aren't they made bigger? They don't necessarily have to become heavier, since the loading per square inch/mm of material decreases proportionately. They don't become harder to balance. They do however become harder from a clearance perspective, and I suspect this is the real problem. But that seams like an easy obstacle to overcome - just mount them higher.
Taken this idea further, isn't it fair to also assume that a fanjet engine also would benefit from a bigger fan? Newer fanjets seem to be getting bigger and bigger (as consumption goes down), so something's afoot. Obviously, at some point the fan will get so big, that it would be prohibitive to encase it. Drag, and structural retaining abilities (if a blade comes off would) make it too big. And then were basically going to end up with a un-shrouded fanjet. Bit like a turboprop but with more and bigger blades. Come to think of it - hasn't this been done?
Please share your valuable ideas.
It is a well known fact within the helicopter world that the bigger the main rotor, the less power it needs to produce lift. It also makes less noise, since it turns slower.
With this in mind, how come most GA planes have such small props? This makes them noisy and producing less thrust. Why aren't they made bigger? They don't necessarily have to become heavier, since the loading per square inch/mm of material decreases proportionately. They don't become harder to balance. They do however become harder from a clearance perspective, and I suspect this is the real problem. But that seams like an easy obstacle to overcome - just mount them higher.
Taken this idea further, isn't it fair to also assume that a fanjet engine also would benefit from a bigger fan? Newer fanjets seem to be getting bigger and bigger (as consumption goes down), so something's afoot. Obviously, at some point the fan will get so big, that it would be prohibitive to encase it. Drag, and structural retaining abilities (if a blade comes off would) make it too big. And then were basically going to end up with a un-shrouded fanjet. Bit like a turboprop but with more and bigger blades. Come to think of it - hasn't this been done?
Please share your valuable ideas.